Glow starting relay for fluorescent lamps



March 15, 1949. c. H. HODGKINS 2,464,748

GLOW STARTING RELAY FOR FLUORESCENT LAMPS v, w

Filed June 14, 1945 INVENTOR ATTORNEY Patented Mar. 15, 1949 UNITED STATES GLOW STARTING RELAY FOR FLUORESCENT LAMPS Application June 14, 1945, Serial No. 599,333

The present invention relates to fluorescent lamp circuits and particularly to a starting relay or switch therefor of the type now commonly referred to as the no-blink which operates to prevent intermittent repetitious flashing of a fluorescent lamp when the latter becomes defective, and constitutes an improvement on the structure such as shown in Patent No. 2,355,476, issued August 8, 1944, to Roy M. Smith and John Steegstra and assigned to the same assignee as the present invention.

Starting relays of this general type are now well known in the art but have heretofore been of the resistance heater type in their entirety or of the combined glow switch and thermal type. In th former type normal as Well as lock-out operation are dependent upon the heat generated by current flow through one or more resistance elements while in the latter type only the look-out operation utilizes the heat generated by a resistance. Since both types are contained within a metallic or plastic casing which is closed to the atmosphere substantial heat is accumulated therein particularly from prolonged retention of the relay in the lock-cu position of the relay.

Moreover, these resistance heating elements are necessarily of small size due to space requirements and because of the wattage required for their operation are too frequently subject to deterioration and change in their ohmic value after sustained operation for prolonged periods of time in locking-out a defective lamp which not only changes the operating characteristics of the relay but greatly shortens its useful life.

It is accordingly an object of the present invention to provide a starting relay for fluorescent lamps of the no-blink or lock-out type and. wherein a resistance heater unit is unnecessary for its operation.

Another object of the present invention is the provision of a no-blink starting relay for fluorescent lamp wherein operation is dependent upon a glow discharge in a vitreous container and thus very little extrinsic heat is developed during any phase of its operation.

Still further objects of the present invention will become obvious from the accompanying 4 Claims. (Cl. 315-100) 2 starting relay of the present invention during one phase of its normal operation.

Figure 2 is an entirely schematic view similar to Fig. 1 showing the starting relay during another phase of its normal operation.

Figure 3 is a schematic view similar to Fig. 2 but showing the starting relay of the present invention in still another phase of its operation.

Figure 4 is a schematic illustration similar to the preceding figures but showing the relay of the present invention in its lock-out position to prevent blinking of the lamp in the event the latter becomes defective.

Figure 5 is a cross-sectional view of the complete starting relay for attachment to the customary socket.

Referring now to the drawings in detail, and particularly to Fig. 1, a fluorescent lamp 5 is therein shown provided with a pair of thermionic electrodes 6 and 1. One end of the electrode 6 is connected to one side of the supply source Ll, of the customary domestic potential of 115-230 volts, through an inductance element 8 and main line switch 9, while one end of the electrode 1 is connected to the other side of the supply source L2. The series heating circuit is completed by the starting relay, shown generally at In, which connects the remaining ends of the thermionic electrodes 6 and 1 to ether.

By reference now to Fig. 5 it will be seen that the starting relay it comprises a casing or housing 4'2 of metal or plastic enclosing the various elements and provided with a pair of terminals 13 and It for engaging the customary socket. Since the elements within the casing l 2 are shown on a larger scale and schematically in the remaining figures reference may be had thereto.

As shown in Fig. 1, the relay Hi comprises a I glow switch! 5 of the usual construction now well known in the art and of the type shown and describedin Patent No. 2,228,210, issued January 7,

1941, to R. F. Hays, Jr. Briefly stated, such glow element'deflectable under the heat generated by the ensuing glow discharge into contact with the" other electrode ll.

ing condenser i8 is also housed within the casing A radio frequency suppress- I2 and is connected directly to the socket terminals I3 and I4.

In addition, a further glow relay I9 is housed within the casing I2 which comprises a vitreous envelope 2!] provided with an ionizable medium therein at a suitable pressure and corresponding to that within the glow switch I5. As will be noted, the glow relay I9 is provided with two stationary electrodes 22 and 23 and a U-shaped bimetallic electrode 24 similar to the bimetallic electrode I6 of the glow switch I5. However, in this glow relay the. bimetallic electrode 24 is normally in contact with the stationary electrode 23, as shown in Figs. 1, 2 and 3, which thus completes the Series heating circuit to the lamp electrodes 6 and I upon operation of the glow switch I5.

When the main switch 9 is closed substantially the full voltage of the supply source LI,

L2 is impressed across the normally spaced electrodes I6 and I1 of the glow switch I15 sincethe electrodes 23 and 24 of the glow relay I9 are normally in engagement with each other. A glow discharge, as shown in Fig. 1, accordingly ensues in the glow switch I5 with heating and attendant deflection of its. bimetallic electrode I6 into engagement with the stationary electrode II. This short-circuits the discharge as shown in Fig- 2 with the result. that. the bimetallic electrode begins to cool and. separates from the stationary electrode I'I.

At the instant of separation a high voltage surge is. induced across the lamp electrodes 6 and I by the inductance 8 which initiates a discharge in the lamp 5, as shown in Fig. 3-. Once the dis.- charge is started in the lamp 5, the voltage drop across. the lamp is such that the voltage then impressed across the electrodes l6 and I! of the glow switch I5. is insufiicient to again initiate a. glow discharge until after extinguishment of the lamp. The cyclic operation of the glow switch t5 as above described requires a matter of only a few seconds and if for any reason the discharge is not-initiated in. the lamp 5, the glow switch l5 continues its cyclic operation because the voltage across its electrodes I6 and I'lis always high. enough to re-establish a discharge, until the. lamp actually starts;

However, should the lamp become defective, such. as by deactivation of the electrodes or the: like, the continued cyclicv operation of the glow switch I5 in a futile attempt to start the lamp causes a continuous glowing of the lamp electrodes followed by periodic flashing which becomes a constant annoyance. To eliminate this undesirable condition, the glow relay I-9- then operates after a short interval of cyclic operation of the glow switch I5.

It will be noted that during the cyclic operation of the glow switch in the manner above described, the electrodes 23 and 24 of the glow relay t9 have remained incontact with each other. However, each time a glow discharge is initiated; in the glow switch IS, a simultaneousglowdischarge also. occurs in thev glow relay I9 between its stationary electrode 22 and the bimetallic electrode 214, asshown: in Fig. 1. Since thestationary electrode 22 is connected.- to the terminal I3 through a low resistance 25, however, the current flowing through the discharge between the-stationary electrode 22' and. bimetallic electrode 24 is; much. lessthanv that across the l w discharge in the glow switch. I5, so.that the discharge in the glow relay I 9 must; continue.- for a longer period of time toheat the bimetallic=electrode 24 than is required in the glow switch I5. As a result, during normal operation of the glow switch I5, the ensuing simultaneous glow discharge between the electrodes 22 and 24 of the glow relay I9 has no effect on the operation of the latter. Also since the resistance 25 is of relatively low ohmic value substantially little heat is generated thereby.

Upon the continued cyclic operation of the glow switch I5 beyond a reasonable number of operations because of failure of the discharge lamp 5, the simultaneous discharge in the glow relay I9 finally heats the bimetallic electrode 24 of the latter causing it to deflect away from its stationary contact 23, as shown in Fig. 4. Should this require too great a time lapse, it may be desirable in some instances to make the electrode 23 of a high resistance contact material, such as carbon. or the like, to develop heat and assist the intermittent glow discharge occurring simultaneous with the discharge in the glow switch I5, in causing deflection of the bimetallic electrode 24 of the glow relay I9.

Separation of these electrodes 23 and 24 and the engagement of the bimetallic electrode 24 with stationary electrode 22 immediately shortcircuits the glow switch I5 so. that it no longer operates and the full available voltage is impressed across the stationary electrodes 22 and 2 3 of the glow relay I9. The discharge is thus not extinguished irr the relay I9 upon separation of the electrodes 24 and 23 but continues between the two stationary electrodes thus continuing to heat the bimetallic electrode 24, which maintans it separated from the stationary electrode 23. Moreover, the ohmic value of the resistance 25' is such that the formation of an arc discharge is prevented and only sufficient current flows in the resulting glow discharge between. the electrodes 22 and 23 to maintain the bimetallic electrode 24 floating between the electrodes 22 and 23 or in contact with the electrode 22, as shown in Fig. 4, during the lock-out or no-blink operation of the relay as shown by this latter figure. When the circuit is interrupted either by opening of the main line switch 9 or replacement of the defective lamp 5, the relay I0 is automatically restored to normal operating condition. If desired the resistance 25 may be dispensed with and the bimetallic electrode 24 of the glow relay made sufliciently massive so that the glow discharge requires substantially the same period of time as when the current is limited by the resistance 25, before the bimetallic electrode 25 deflects and disengages the electrode 22. However, as above noted, it is preferable to employ the resistance 25 not only to provide the desired time delay by limiting the current but also to prevent the ensuing glow discharge in the glowrelay 20 from deteriorating into an arc discharge.

It. thus becomes obvious to those skilled in the art that a starting. relay for fluorescent lamps is herein provided which is of the no-blink type and wherein a glow relay in combination with a glow switch is employed which operates after the lapse of' a suitable period of repetitious operation. of the glow switch in a futile attempt to start a. defective lamp, to prevent blinking of the lamp. Moreover,,by the utilization of such glow relay, the necessity for a resistance heater is eliminated, thus avoiding appreciable extrinsic heat. Also the operating characteristics of suchglow relay remain substantially uniform throughout useful life which does not occur with the em ployment of resistance heaters in the thermal relays of the prior art.

'Although one specific embodiment of the present invention has been shown and described, it is to be understood that still other modifications thereof may be made without departing from the'spirit and scope of the appended claims.

1 I claim:

1i. A relay unit for starting and operating a discharge lamp provided with a filamentary electrode and for preventing flashing thereof upon such lamp becoming defective comprising a casing, a glow switch disposed in said casing comprising an envelope having a gaseous atmosphere therein and provided with a pair of electrodes one of which is a bimetallic element and adapted to be connected to the filamentary electrode of the discharge lamp and cyclically operable upon the application of a potential thereto and to the discharge lamp to establish a glOW discharge in said glow switch with attendant heating of its bimetallic element and movement thereof into contact with the other electrode of said pair to repetitiously complete a starting circuit to the lamp until a discharge occurs therein, and a glow relay disposed in said casing comprising an envelope having a gaseous atmosphere therein and provided with a pair of electrodes one of which is a bimetallic element and normally engaging each other to complete a circuit to said glow switch, and having another electrode for supporting a glow discharge with one of the electrodes of said pair simultaneously with the occurrence of a cyclic discharge in said glow switch in a futile attempt to start a defective lamp to cause heating of its bimetallic element and disengagement thereof from the other electrode of said pair with attendant short-circuiting of said glow switch to prevent further cyclic operation of the latter and repetitious flashing of the defective lamp.

2. A relay unit for starting and operating a discharge lamp provided with a filamentary electrode and for preventing flashing thereof upon such lamp becoming defective comprising a casing, a glow switch disposed in said casing comprising an envelope having a gaseous atmosphere therein and provided with a pair of electrodes one of which is a bimetallic element and adapted to be connected to the filamentary electrode of the discharge lamp and cyclically operable upon the application of a potential thereto and to the discharge lamp to establish a glow discharge in said glow switch with attendant heating of its bimetallic element and movement thereof into contact with the other electrode of said pair to repetitiously complete a starting circuit to the lamp until a discharge occurs therein, and a glow relay disposed in said casing comprising an envelope having a gaseous atmosphere therein and provided with a pair of electrodes one of which is a bimetallic element and normally engaging each other to complete a circuit to said glow switch, and having another electrode for supporting a'glow discharge with one of the electrodes of said pair simultaneously with the occurrence of a cyclic discharge in said glow switch in a futile attempt to start a defective lamp to cause heating of its bimetallic element and disengagement therecf from the other electrode of said pair with attendant short-circuiting of said glow switch to prevent further cyclic operation of the latter and repetitious flashing of the defective lamp, and means within said casing and connected with said another electrode to limit 6-: the current in the glow discharge occurring in said glow relay to cause a slight delay in the disengagement of the electrodes of said pair until said glow switch has cyclically operated for a.-

suificient period of time to start a lamp free from defects.

3. A relay unit for starting and operating a discharge lamp provided with a filamentary electrode and for preventing flashing thereof upon such lamp becoming defective comprising a C35! ing, a glow switch disposed in said casing comprising an envelope having a gaseous atmosphere therein and provided with a pair of elec-' trodes one of which is a bimetallic element and adapted to be connected to the filamentary electrode of the discharge lamp and cyclically operable upon the application of a potential thereto and to the discharge lamp to establish a glow discharge in said glow switch with attendant heating of its bimetallic element and movement thereof into contact with the other electrode of said pair to repetitiously complete a starting circuit to the lamp until a discharge occurs therein, and a glow relay disposed in said casing comprising an envelope having a gaseous atmosphere therein and provided with a pair of electrodes one of which is a bimetallic electrode and normally engaging each other to complete a circuit to said glow switch, and having a third electrode for supporting a glow discharge between the latter and said bimetallic electrode simultaneously with the occurrence of a cyclic discharge in said glow switch for heating said bimetallic electrode to cause disengagement thereof from the other electrode of said pair upon continued cyclical operation of said glow switch in a futile attempt to start a defective discharge lamp, and to cause attendant shortcircuiting of said glow switch with continuation of the discharge in said glow relay between the bimetallic electrode and said third electrode maintaining disengagement of the normally engaged pair of electrodes thereof until replacement of the defective lamp.

4. A relay unit for starting and operating a discharge lamp provided with a filamentary electrode and for preventing flashing thereof upon such lamp becoming defective comprising a casing, a glow switch disposed in said casing comprising an envelope having a gaseous atmosphere therein and provided with a pair of electrodes one 'of which is a bimetallic element and adapted to be connected to the filamentary electrode of the dis-charge lamp and cyclically operable upon the application of a potential thereto and to the discharge lamp to establish a glow discharge in said glow switch with attendant heating of its bimetallic element and movement thereof into contact with the other electrode of said pair to repetitiously complete a starting circuit to the lamp until a discharge occurs therein, and a glow relay disposed in said casing comprising an envelope having a gaseous atmosphere therein and provided with .a pair of electrodes one of which is a bimetallic electrode and normally engaging each other to complete a circuit to said glow switch, and having a third electrode for supporting a glow discharge between the latter and said bimetallic electrode simultaneously with the occurrence of a cyclic discharge in said glow switch for heating said bimetallic electrode to cause disengagement thereof from the other electrode of said pair upon continued cyclical operation of said glow switch in a futile attempt to start a defective discharge lamp, and to cause attendant 1; slroiztvcirouiting; or said el'ow' switch with .continuation; of thedischarge in said, glow relay be-- tween the bimetallic electrode and said third electrode maintaining disengagement of the normaliy engaged pair of electrodes thereof until replacement of the defective lamp, and a resistznce-irr said casingv connected in series with one or the discharge supporting electrodes of said glow'relayto limit the current in the discharge to: cause aslight delay in the disengagement of thabimetallicelectrode from the other electrode of said'pair until said glow switch has repetitious- 13 operated. for" a suflicient period of time to start alampfreevfrom-defects.

CHARLES- H. HODGKINS;

summons; crrm The following, references are or record in the file of this patent:

UNITED' STATES PATENTS- Number Name DDR- 2,343,262 McCarthy Mar. 3,1944 2,356,813 Betz Aux. 29; 1944 m 2,379,115 Thayer June 26, 1945 FOREIGN PA'I'ENTS" Number Country Date 118,042 Australia. Jan. 18., 184i 

